1. Field of the Invention
The present invention relates generally to a flow display method, and more particularly to a method of displaying the state of flows in a planar area defined in a three-dimensional flow.
2. Description of the Related Art
An ultrasonic pulse Doppler method has been put to practical use which utilizes the Doppler effect of ultrasonic waves to observe a flow velocity profile of a fluid in a plane to be observed. The ultrasonic pulse Doppler method is used for observation of intracardiac blood flow velocity, for instance. In the ultrasonic pulse Doppler method, an ultrasonic probe sends and receives a pulse-like ultrasonic beam for scanning a plane to be observed to thereby acquire flow velocity information at each point in the plane. As is well known, the thus acquired velocity information at each point is displayed in such a manner that a flow approaching the ultrasonic probe and a flow moving away therefrom are colored differently, with the magnitude of the velocity being indicated by the luminance. For example, the blood flow velocity profile obtained by the pulse Doppler method is displayed in color superposed on a cardiac ultrasonic tomographic image so as to be utilized for the intracardiac blood flow diagnosis.
A Doppler radar making use of Doppler effect of radio waves is known as an apparatus utilizing the Doppler method, and is used for weather observation such as observation of the flow of clouds.
Such a velocity observation method utilizing Doppler effect has in principle a restriction that it is possible to obtain the velocity information only in the direction of send and receipt of the observation beam (ultrasonic wave or radio wave). Therefore, conventional ultrasonic diagnostic apparatuses or the like have typically provided a display of only the velocity components in the direction of send and receipt of the observation beam at each point.
The velocity observation method utilizing Doppler effect has acquired and displayed information on the flow velocity profile in a two-dimensional scanning plane (i.e., observation plane) which is scanned by the observation beam such as an ultrasonic wave or radio wave.
However, the actual flow is a three-dimensional flow, and the flow velocity profile obtained by the ultrasonic diagnostic apparatuses or the like merely represents components in the scanning plane of the three-dimensional flow. In addition, the components represented thereat are eventually only the velocity components in the beam direction. Although the actual flow has a three-dimensional inflow into and outflow from a planar area to be observed, no consideration has hitherto been given to such inflow and outflow with no display thereof.
Some ultrasonic diagnostic apparatuses have combined Doppler velocity measurement values obtained by the ultrasonic beams in two directions to acquire a two-dimensional flow velocity. The conventional apparatuses of this type have typically provided a display of the velocity profile such that a flow velocity at a lattice point defined in the plane to be observed is displayed in the form of a vector with arrow. That is, such apparatuses have also merely allowed a display of the two-dimensional flow velocity components in the plane to be observed, with no display of the state of inflow/outflow of the three-dimensional flow into/from the plane to be observed.
Although the above description has been made of the apparatuses observing the flow by use of the Doppler method by way of example, other general systems for the display of the flow such as fluid simulation systems have also not provided a display of the flow in the two-dimensional planar area defined in a three-dimensional flow in the form of inclusion of the state of the three-dimensional inflow and outflow.